There is a great need in the marketplace for contrast agents which will produce high definition images of the vasculature of different tissues . Conventional water-soluble contrast media rapidly diffuses following injection, providing contrast for only a very short time. The objective of this research is to isolate and identify tissue-specific endothelial membrane proteins exposed to the lumen of the vasculature. These proteins are exposed on the luminal surface and therefore are directly accessible to agents introduced into the blood. Using a ligand which binds to a tissue- specific target on the luminal surface of blood vessels can direct high concentrations of contrast media to the vasculature of a tissue for the production of high definition images of blood vessels and capillaries. A proprietary method enables the isolation of proteins exposed on the luminal surface of the vascular endothelium. Tissue-specific proteins can be identified using standard mass spectroscopy and microsequencing methods. This subset of proteins will allow the design of ligands (small molecules or antibodies) to be used for tissue specific localization of in vivo diagnostic imaging contrast media. PROPOSED COMMERCIAL APPLICATIONS: The identification of blood-accessible, tissue-specific target molecules will lead to the tissue-directed delivery of contrast agents which will facilitate cheaper and higher definition imaging of the vasculature. Endosite will obtain proprietary positions on these targets and their ligands and use this position as leverage in generating partnerships with the established in vivo imaging companies.